Abstract:
Across the Potomac River from the location of the DFI47 Annual Conference, in Alexandria, VA, two large permanent anchored walls with a decorative shotcrete face, were recently constructed at the same project site location for a new Multi-Family and Town Home Development. The project arose as a design-build approach with review by the Fairfax County Geotechnical Review Board. The parameters were driven by a severely varying site geology of the Potomac group sediments. This group contained clay/silt terrace deposits overlying coarser grained materials. The soils were overly consolidated and exhibited potential for slickensides from relief of horizontal stresses from past erosion. Difficult site geology led to a design of long strand anchors and deep soldier piles. As the construction developed, the problematic soil conditions of varying soil layers and water issues encountered when drilling resulted in adjusting techniques to complete the project. The overall size of the two-permanent wall’s spanned both 800 feet long and 1,000 feet long with a maximum height reaching 40 feet at the tallest section.